}

    // Test getImageFilename with custom settings
    @Test
    public void test_getImageFilename_customSettings() {
        thumbnailManager.setImageExtention("jpg");
        thumbnailManager.setSplitSize(5);
        thumbnailManager.setSplitHashSize(20);

        String docid = "1234567890abcdef";
        String filename = thumbnailManager.getImageFilename(docid);
        assertNotNull(filename);